This invention relates to mechanically operable plug devices for sealing pipelines or conduits. Particularly, this invention relates to mechanical plugs for sealing clean-out tees or access ports of low pressure pipelines or conduits.
Clean-out tees or access ports to pipelines are typically found in drain pipes, such as in basement floor drains, and also in horizontal or vertically disposed conduits which may require entry for cleaning or inspection purposes. These access ports or clean-out tees are typically circular structures extending perpendicularly from the pipeline. The ports usually have a relatively short length and are internally threaded to receive a threaded closure cap. After continued use, the access port threads often become damaged so that it is difficult or impossible to secure the threaded closure cap therein. Thus, the costly replacement of the damaged access port structure joined in the pipeline is often required.
The mechanical plug device of this invention permits the user to seal and plug the clean-out tees, particularly when slightly damaged. The device provides a stopping mechanism that seals clean-out tees and has a structure which can be quickly and effectively secured to seal the entry port. The plug device has a narrow or thin structural configuration which provides a flush sealing structure with the exterior of the entry port to diminish protruding obstacles and also flush within the interior of the pipeline to diminish flow obstruction.
In the past, various types of pipe plug devices have been proposed or utilized for sealing pipeline networks, such as sewer lines. For example, Applicants' assignees' U.S. Pat. No. 4,493,344, issued 15 January 1985, is for a mechanical plug device. The device of the '344 Patent is a hand operable device for temporarily sealing the interior of a pipeline. In contrast to the '344 structure, the more permanent and thinner mechanical plug for clean-out tees of this invention is specifically designed for use in threaded clean-out tees or access ports. Applicants' assignees' U.S. Pat. No. 4,817,671, issued 4 April 1989, is for a high pressure mechanical plug device for sealing and locking into a high interior pressure pipeline. In contrast to the '671 structure, the thinner mechanical plug of the present invention has structure for use in threaded access ports of low pressure pipelines.
Other prior art devices have also been proposed or utilized to seal pipelines and they primarily relate to either pneumatic or mechanical type plugs. With respect to the present invention, however, pneumatic plugs typically have a relatively larger body length and which utilize hollow rubber cylinders that are inserted into pipelines and then expanded by a fluid. Mechanical type plugs usually also have a relatively substantial thickness or width and which are typically constructed of plate structures which combine with various cooperating components to compress hollow rubber cylinders or sealing ring structures for expansion to contact and seal against the interior pipeline walls. These prior art devices have often been expensive to manufacture and have not provided a relatively thin, simple and economically constructed mechanical plug that is suitable for providing effective seals for pipe ends and, particularly, for threaded pipe access ports.
The mechanical plug for clean-out tees according to the teachings of this invention overcome the difficulties, limitations and other shortcomings of these prior art devices.